Device and method for treating a medical fluid and medical cassette

ABSTRACT

An apparatus for treating a medical fluid is provided which includes a treatment machine having a coupling surface, with a cassette made of a hard part having liquid-conducting passages which are covered by a flexible film being able to be coupled to the coupling surface of the treatment machine. A corresponding medical cassette is also provided. An air-free coupling of the flexible film of the cassette to the treatment machine is ensured in that air can be sucked out areally along a plane between the flexible film and the coupling surface during the coupling process and/or with a coupled cassette. A method for coupling the cassette and a method for checking the leaktightness of the cassette via the vacuum control of the air suction is also provided.

This is a continuation of U.S. patent application Ser. No. 12/733,592,filed Mar. 10, 2010, and issuing as U.S. Pat. No. 8,470,171 on Jun. 25,2013, which is a national stage of PCT/EP08/003,978 filed May 16, 2008and published in German, which claims the priority of DE No. 10 2007 042964.0, filed Sep. 10, 2007, and hereby claims the priorities thereof towhich it is entitled.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for treating a medicalliquid which includes a treatment machine having a coupling surface,with a cassette made of a hart part having liquid-conducting passageswhich are covered by a flexible film being able to be coupled to thecoupling surface of the treatment machine. The present invention furtherrelates to a medical cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film, withthe cassette being able to be coupled to the coupling surface of thetreatment machine. The present invention further relates to an apparatusfor treating a medical liquid which includes a treatment machine havinga coupling surface, with a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film. Thepresent invention further relates to a method for coupling a cassettemade of a hard part having liquid-conducting passages which are coveredby a flexible film to the coupling surface of a treatment machine forthe treatment of a medical liquid as well as to a method for checkingthe leaktightness of such a medical cassette.

2. Description of the Related Art

The treatment machine can be a blood treatment machine such as is usedin hemodialysis or in peritoneal dialysis. In such a use, the medicalcassette includes the blood-conducting or dialysis liquid-conductingpassages and is in communication with actuators and sensors of thetreatment machine via the coupling surface. The medical cassette canthus be configured as a cost-effective disposable part, whereas theactuators for the control of the liquid flow through the cassette andthe sensors are integrated into the treatment machine for the leveldetection or for the pressure measurement.

Such medical cassettes configured as disposable articles comprise inthis connection a thin-walled three-dimensional hard plastic part havinga planar peripheral contact edge and various recesses (chambers, websand passages). Medical liquids such as dialysate or blood can now beconducted in the chambers and passages formed by these three-dimensionalstructures of the hard plastic part. The contact plane of the cassetteis closed in a liquid tight manner by a flexible film, advantageously apolymer film which is peripherally connected, in particular weldedand/or adhesively bonded, to the contact edge of the hard part. Themedical cassette is pressed onto the coupling surface of the treatmentmachine in use with the flexible film so that actuators and sensors ofthe treatment machine lie on the polymer film. In addition, the flexiblefilm is pressed together with the webs of the cassette by this pressingand thus provides a fluid tight separation of the liquid-conductingpassages in the hard part by the webs and the flexible film.

The coupling surface of the treatment machine accordingly usually hasactuators, sensors and pressing force transmission surfaces. Theactuators and sensors of the blood treatment machine are arranged inthis context in the coupled state of the cassette opposite theliquid-conducting passages of the cassette. The actuators can herebyform valves by the pressing down of the film in that the flexible filmis pressed into regions of the liquid-conducting passages and closesthem. The sensors, for example, measure the pressure or temperature ofthe liquid located in the liquid-conducting passages. The pressing forcetransmission surfaces press the flexible film against sealing webs ofthe hard parts which surround the liquid-conducting passages to sealthem with respect to one another and toward the rest of the cassette. Inthis connection, the coupling surface is usually formed by a planarsurface of a support member which is made from metal, for example, withreceivers for the sensors and the actuators being provided in thesurface, and by the sensors inserted into these receivers in planarfashion.

A flexible mat made, for example, of silicone or another elastomericmaterial, is usually arranged on the coupling surface of the treatmentmachine. This has the advantage that the sensor surfaces are protectedagainst environmental influences and the machine surface is moreoverliquid tight and thus may ideally be hygienically cleaned. The flexiblemat in this context represents a part of the treatment machine to whichthe cassette is coupled as a disposable part. The operation of theactuators is ensured by the flexibility of the mat. In addition, theflexible film can be pressed well to the coupling surface via theflexible mat, which permits a good contact with the actuators, sensorsand pressing force transmission surfaces. The treatment machine can,however, also be operated without a flexible mat so that the flexiblefilm lies directly on the coupling surface and the sensors and actuatorscouple directly to the film.

There is, however, the difficulty with known systems in the coupling ofsensors to the film surface of achieving a good coupling to obtaincorrect measured values. In particular, air which is trapped in thetransmission path between the flexible film and the sensor surface onthe insertion of the cassette, produces a falsification of the measuredresults. This applies to pressure sensors (in particular on themeasurement of pressures which are less than the environmentalpressure), but also in level detection and likewise to actuators such asvalves. Unwanted air inclusions between the outer surface of theflexible film and the mat surface of the flexible mat lying thereon or,if no mat is used, of the coupling surface of the treatment machinelying thereon, should therefore be eliminated on the coupling. Thisusually takes place by air suction. In this context, however, the fluidcontacting of this space is complicated. There is in particular theproblem that a self-sealing of the film takes place by an application ofthe film onto the mat or onto the coupling surface so that air islandsremain.

It is therefore known from DE 101 57 924 C1 and DE 102 24 750 A1 torealize the air transport by means of integrated mat passages,predetermined in a defined manner, on the rear side of the machine matat the machine side. The air line from the surface of the flexible filmthrough the mat to the air passages arranged on the machine side takesplace locally through uninterrupted slots in the region of the matpassages. The air transport however, hereby only takes place atprecisely defined points of the flexible film of the cassette at whichthe air is sucked off through the slots in the mat to the mat passagesarranged on the machine side. These mat passages therefore have to belocated in the region of the liquid-conducting passages of the cassetteto ensure a good suction there, which can lead to safety problems. Sucha machine mat having integrated mat passages and slots is moreovercost-intensive in manufacture and complex and/or costly in cleaning. Thesensor surface is thus also no longer ideally protected fromenvironmental influences and hermetically sealed by the mat so thathygienic problems also result. There is moreover the need to furtherimprove the reliability of the air suction since the inclusion of airislands can still occur due to the only local suction through the slots.

SUMMARY OF THE INVENTION

It is therefore the object of the present invention to achieve acost-effective, reliable and hygienic air suction.

This object is solved in accordance with the invention by an apparatusfor treating a medical liquid that includes a treatment machine having acoupling surface, with a cassette made of a hard part and havingliquid-conducting passages which are covered by a flexible film beingable to be coupled to the coupling surface of the treatment machine. Inaccordance with the invention, in this connection, in the coupled stateof the cassette, a layer of an air-permeable porous material is arrangedbetween the flexible film and the coupling surface, at least in partialregions, and air can be sucked out areally through the layer during thecoupling process and/or with a coupled cassette. In accordance with theinvention, air is no longer only selectively sucked out at some pointsthrough the slots in the flexible mat so that air islands may remain, asin the prior art, but is rather sucked out areally through the layer ofan air-permeable porous material. A full-area suction of the air out ofthe region between the flexible film and the coupling surface is therebypossible, with air inclusions, which can never be precluded with onlylocal suction, being reliably prevented. In addition, the poorlycleanable design of the flexible mat having mat passages can bedispensed with and a flexible mat can be used substantially withoutopenings or no mat at all can be used.

It is possible in this context in accordance with the invention that aircan already be sucked out particularly advantageously during thecoupling process, in particular shortly before the end of the couplingprocess. The contact pressure is increased up to a maximum value in thisconnection on the coupling of the cassette. The suction can already bebegun in this context as soon as the cassette contacts the couplingsurface, but before the cassette is pressed on with a maximum pressingforce. A vacuum can already be sucked out during this short phase. Theporous material or the structuring is in particular compressed stillless strongly in this phase and thus conducts air better. The suction ofthe air can, however, also take place with a completely coupledcassette.

The air can advantageously be sucked out through the layer of anair-permeable porous material along the plane of the layer in thisconnection. An air removal along the coupling plane is thereby madepossible, whereas simultaneously the actuators and sensors can have aneffect perpendicular to the coupling plane. It is sufficient in thisconnection to have fluid contact to the space between the film and thecoupling surface at one or more suction points and to connect the spaceto a suction apparatus, with the air being sucked out areally from therealong the coupling plane. If a mat is provided, the flexible mat whichotherwise has no perforations can have openings at one or fewer pointsfor fluid contacting of the air-permeable porous layer.

Due to the layer made of an air-permeable, in particular porousmaterial, the vacuum for suction can act in the whole region of thelayer made of an air-permeable porous material, which makes possible afull area, reliable suction. The material of the layer is advantageouslyair-permeable both along the main plane of the layer and alsotransversely to the main plane of the layer. The air transport canhereby in particular also take place in the material layer along itsmain plane, whereby the air between the surface of the flexible film andthe coupling surface is reliably sucked out.

The layer of an air-permeable porous material is advantageously arrangeddirectly on the flexible film in the coupled state of the cassette. Adirection suction of the air from the surface of the flexible filmthereby results so that a reliable coupling is made possible.

Further advantageously, the layer made of an air-permeable porousmaterial comprises a nonwoven material. Such a nonwoven material permitsthe air transport described above, with it providing a uniform contactbetween the coupling surface and the film and thus between the sensorsand actuators and the film, but simultaneously ensures the areal suctionin the plane between the flexible film and the coupling surface or theflexible mat.

Further advantageously, the layer of an air-permeable material isarranged over the whole area of the flexible film. A cost-effective andsimple possibility thus results to permit the air suction over a fullsurface of the layer made of an air-permeable material. It is, however,also possible for specific applications only to provide such a layer ofan air-permeable material in part regions.

Further advantageously, the cassette is pressed with the couplingsurface in the coupled state, with the pressure transmitted over thelayer made of an air-permeable material orthogonally to its plane duringthe coupling process and/or with a coupled cassette pressing the film ina fluid tight fashion with the liquid-conducting passages of the hardpart of the cassette, but with the layer made of an air-permeablematerial remaining air-permeable along its plane. The layer made of anair-permeable porous material can thus transmit the pressure requiredfor the sealing of the liquid-conducting passages by the interactionbetween the webs of the hard part and the film which is pressed onto thewebs. At the same time, however, it remains gas-permeable along itsplane and thus provides an areal suction of the air between the film andthe coupling surface.

Further advantageously, the treatment machine has a flexible mat, inparticular a silicone mat, arranged on the coupling surface and thecassette can be coupled to the coupling surface of the treatment machinevia the flexible mat.

In an advantageous embodiment, the treatment machine has a flexible matarranged on the coupling surface, with the cassette being able to becoupled to the coupling surface of the treatment machine via theflexible mat and a layer of an air-permeable material being arrangedbetween the flexible film and the flexible mat in the coupled state ofthe cassette. The flexible mat can hereby seal the coupling surface in afluid tight manner and thus provide an arrangement which is particularlysimple to clean and is hygienic, while the suction takes place via theair-permeable layer arranged between the flexible mat and the flexiblefilm. Silicone or another suitable elastomer can be used as the materialfor the flexible mat in this context. In this connection, a porousmaterial layer such as a nonwoven material in turn proffers itself as anair-permeable layer.

In the present invention, it is, however, also possible due to the arealsuction of the air along the coupling plane to dispense with theflexible mat between the flexible film of the cassette and the couplingsurface of the treatment machine and only to provide a layer of anair-permeable porous material such as a nonwoven so that the flexiblefilm of the medical cassette lies directly on the coupling surface ofthe treatment machine via the layer made of an air-permeable materialwithout a mat therebetween and the air suction takes place directlybetween the coupling surface and the flexible film.

The present invention further includes an apparatus for treating amedical liquid which includes a treatment machine having a couplingsurface and a flexible mat arranged on the coupling surface, with acassette made from a hard part having liquid-conducting passages, whichare covered by a flexible film, being able to be coupled to the couplingsurface of the treatment machine via the flexible mat, with the flexiblemat comprising an air-permeable material and being configured such thatair is sucked out in a region of the flexible mat without openingsduring the coupling process and/or with a coupled cassette, and indeedalong the plane of the flexible mat and/or through the flexible mat. Bythe use of a permeable mat material, it is thus possible to dispensewith an additional layer made of an air-permeable material since theareal suction takes place via the flexible mat itself. The supply of thevacuum can then take place via corresponding passages in the couplingsurface of the treatment machine. Since thin silicone layers have acertain permeability for air, the flexible mat can be formed of siliconeand can be made very thin in the regions in which air should be suckedout so that air can be sucked out directly through the mat byapplication of a correspondingly high vacuum. It is thus possible todispense with slots through the mat which make cleaning more difficult.The coupling surface is moreover further sealed in a liquid tightmanner.

Alternatively or additionally to the layer described above of anair-permeable porous material or to the flexible mat of an air-permeablematerial, however, the surface of the film or the surface of theflexible mat facing the film can have a structuring via which air can besucked out.

The present invention therefore further includes an apparatus fortreating a medical liquid which includes a treatment machine having acoupling surface, with a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film beingable to be coupled to the coupling surface of the treatment machine. Inthis connection, in accordance with the invention, the surface of theflexible film has a structuring through which air can be sucked outalong the structuring of the film during the coupling process and/orwith a coupled cassette. A secure suction of the air out of the regionbetween the film and the coupling surface or mat is thus also possiblealong the coupling plane in that the air is sucked out through thepassages formed by the structuring of the film surface. The structuringthus likewise permits an areal suction of the air and thus prevents theformation of air islands, with it being provided at least in the regionswhere an air-free coupling is required. The structuring in the surfaceof the film is advantageously small enough in this context so that nofluctuations, or only minimal fluctuations, occur in the pressing forcebetween the flexible film and the webs of the hard part, but is largeenough so that the passages arising through the structuring are notcompletely closed by the pressure between the coupling surface or matand the film, but remain air-conducting.

The structuring can take place by stamping of the film surface in thisconnection. Alternatively, a structuring can also be introduced directlyon the extrusion of the film.

It is furthermore possible to apply a structuring to the side of theflexible material facing the film. The present invention thereforefurther includes an apparatus for treating a medical liquid whichincludes a treatment machine having a coupling surface and a flexiblemat, in particular a silicone mat arranged on the coupling surface, witha cassette made of a hard part having liquid-conducting passages whichare covered by a flexible film being able to be coupled to the couplingsurface of the treatment machine via the flexible mat. In thisconnection, in accordance with the invention, the surface of theflexible mat facing the flexible film has a structuring through whichair can be sucked out along the structuring of the flexible mat duringthe coupling process and/or with a coupled cassette. The suction throughthe structuring of the surface of the flexible mat takes place inprecisely the same way as the suction through the structuring of theflexible film such as was described above.

The structuring of the film, however, has the decisive advantage withrespect to a structuring of the surface of the mat facing the film thatthe surface of the mat facing the film can be made smooth and is thuseasy to clean. The cassette is, in contrast, anyway a disposable part sothat it does not have to be cleaned after use, but is disposed of.

Advantageous embodiments of the structuring which can be used both forthe structuring of the flexible film and for the structuring of the matsurface will be described hereinafter.

The structuring advantageously has a net structure and/or ameandering-like and/or a linear structure. The air can be sucked outsimply and reliably areally through a net structure, in particular,advantageously a honeycomb structure. A direct suction in specificregions can, in contrast be achieved by a meandering-like structure.

Further advantageously, the structuring is made anisotropic and/orinhomogeneous. It is thus possible to realize an anisotropic suction bythe selection of the suitable structure in that e.g. the passages aremade larger from left to right than from top to bottom. The structure onthe surface can also be made inhomogeneous. It is, for example, herebypossible to realize a uniform suction of the air in the surface, even ifthe space between the film and the mat is only in fluid contact with thesuction apparatus at one point.

The aspect ratio of the channels which arise is important for theachievable suction power with such a structuring. The width of thepassages is advantageously less than their depth in this context. Thepassages are not closed by such narrow, deep passages on the pressing offilm and mat so that the suction remains possible. The shallower thepassages, the larger the risk of sealing by a partial contact of thefilm on the mat would be. It the passages become too wide, the riskmoreover increases that the pressing on the smooth rear side of the filmwith the webs of the hard part becomes too non-homogeneous and thatleaks occur on this side between the liquid-conducting passages.

In a further embodiment, the structuring of the film surface or of themat surface can extend along the liquid-conducting passages. Only alower volume thereby has to be evacuated so that the time required forthe suction or for an initial leaktightness test is reduced. Inaddition, the air is only sucked out where there is actually a need foran air-free connection between the film and the flexible mat. Such anair-free coupling is, in contrast, not necessary in the regions withoutliquid-conducting passages. The structuring can therefore advantageouslyextend along the liquid-conducting passages in meander-like and/orlinear form.

In this context, the structuring, however, advantageously converges inone or more regions outside the liquid-conducting passages which formsuction points. A simple connection, e.g. with a suction device, canthus take place in these regions outside the liquid-conducting passages,whereas the structuring extending from the suction point into theregions of the liquid-conducting passages provides a reliable suction ofthe air out of these regions.

The structuring advantageously extends substantially perpendicular tothe passage web edge on the transition from the region withliquid-conducting passages to the region outside the liquid-conductingpassages. A uniform pressing of the film with the passage web edges ishereby ensured without the structuring losing its air-conductingfunction due to the pressing.

The structuring advantageously has a spacing from the passage web edgesin the regions in which it does not traverse the passage web edges. Thestructuring is thus only capable of draining in the liquid-wetted filmareas required from a technical process aspect. No air suction isnecessary in contrast in the other regions due to the high contactpressure between the film and the hard part.

The structuring is furthermore advantageously made such that there is nodirect connection between regions of the film with differentliquid-conducting passages. This has the advantage on a rupture of thefilm that the liquid cannot spread over the whole cassette along thestructuring. Ruptures in a region without liquid-conducting passagesthus in particular also remain without consequences. Even on a ruptureof the film in a region of the liquid-conducting passages, the liquid isonly sucked to the suction point along the structuring, whereas a leakbeyond the passage web edges between the liquid-conducting passages isprevented.

However, a good and reliable pressing and air suction can also beachieved on the use of a honeycomb structure which naturally does notextend along the liquid-conducting passages and with which thestructuring is not always perpendicular on the passage web edges. Thesimple and cost-effective manufacture is the advantage of such a design.

The cassette in the method in accordance with the invention isadvantageously pressed with the coupling surface in the coupled state,with the film being pressed in a fluid-tight manner with theliquid-conducting passages of the hard part of the cassette, but withthe structuring along its plane allowing air transport.

The present invention further includes an apparatus for treating amedical liquid which includes a treatment machine having a couplingsurface and a flexible mat, in particular a silicone mat arranged on thecoupling surface, with a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film beingable to be coupled to the coupling surface of the treatment machine viathe flexible mat. In accordance with the invention, air can be suckedout along a plane between the flexible film and the surface of theflexible mat facing the flexible film during the coupling procedureand/or with a coupled cassette. Equipping the flexible mat with thecomplex and/or expensive mat passages and slots which are difficult toclean can hereby be dispensed with. The air can rather be sucked outreliably and simply between the mat surface and the flexible film. Thesuction advantageously takes place via a layer of an air-permeablematerial arranged at least in part regions or via a structuring of theflexible film or of the mat surface. The advantages already describedabove hereby result.

In accordance with the invention, air is thus no longer only sucked outselectively through the slots in the flexible material as in the priorart, but rather areally along the plane between the film and the mat. Itis hereby sufficient to have fluid contact to the space between the filmand the coupling surface at one or more points and to connect the spaceto a suction apparatus, with the air being sucked out areally from therealong the coupling plane between the film and the mat. Thecost-intensive design of the flexible mat with mat passages can thus bedispensed with. In addition, a secure air-free coupling is ensuredbetween the film and the mat without the mat having to have slots sothat a liquid-tight and thus ideally hygienically cleanable machinesurface again becomes possible.

The suction of the air advantageously takes place via a structure whichis arranged in the region between the flexible film and the flexiblemat. An air conduction along the coupling plane is thus made possible,whereas simultaneously the actuators and sensors can have an effectperpendicular to the coupling plane. It is in particular advantageouslya case of an areal structure such as the layer already named above madeof an air-permeable material or a structuring of the surface of the filmor of the mat. A full-area suction of the air out of this region isthereby possible, with air inclusions, which can never be precluded withonly local suction, being reliably prevented.

Further advantageously, the apparatus in accordance with the inventionhas at least one suction device. A vacuum can be made available via thissuction device, said vacuum being connected to the region between theflexible film and the flexible mat or the coupling surface and thusmaking the suction possible. It can be of advantage in this context toimplement the suction device in a multiple fashion to improve the testcapability of the suction device.

Further advantageously, with the apparatus in accordance with theinvention, the air conducting layer is in fluid connection with thesuction device at one or more points outside the region of theliquid-conducting passages independently of via which structure theareal suction is realized. Since the suction takes place along thecoupling plane, it is no longer necessary in the present invention tomake a fluid connection with a vacuum apparatus available directly inthe region of the liquid-conducting passages.

Further advantageously, in the apparatus in accordance with theinvention, the suction takes place via at least one valve arranged inthe coupling surface of the treatment machine. Said valve is opened e.g.by pressing the cassette onto the coupling surface of the treatmentmachine by means of a plunger and then automatically sucks the air outof the air-conducting layer.

Alternatively, the suction can also take place through the cassette. Inthis connection, a suction opening with a hydrophobic membrane can beprovided on the cassette. The suction therefore advantageously takesplace via one or more suction openings which are arranged in the hardpart of the cassette and which are advantageously provided with ahydrophobic membrane. A simple fluid contacting of the air-conductinglayer is hereby possible.

Further advantageously, the apparatus in accordance with the inventionhas an optical sensor for the recognition of leaks, in particular byscattered light wetting detection. A simplified contactless leakdetection hereby results, in particular in conjunction with astructuring of the film surface which varies its reflection propertiesby discharge of liquid, which can be detected by the optical sensor.

Further advantageously, the apparatus in accordance with the inventionhas a control which carries out an automatic suction of the air. In thiscontext, the control controls the suction device and thus automaticallyprovides an air-free coupling of the medical cassette.

Further advantageously, the control carries out an automatic check ofthe leaktightness of the medical cassette. This can be carried out, aswill be described further below, by a check of the vacuum on the airsuction.

Further advantageously, a medical cassette, which will be shown in thefollowing, is used in the apparatus in accordance with the inventionsuch as have already been described.

The medical cassette of the present invention in this context includes ahard part having liquid-conducting passages which are covered by aflexible film, with the cassette being able to be coupled to a couplingsurface of a treatment machine. In this connection, in accordance withthe invention, a structure is arranged on the flexible film throughwhich air can be sucked out along the plane of the film surface duringthe coupling process and/or with a coupled cassette. As already shown indetail with respect to the apparatus for treating a medical liquid, itis hereby possible to ensure a secure and reliable suction of the airbetween the flexible film and the mat or the coupling surface of thetreatment machine. It is of particular advantage in this context for thestructure to form a component of the medical cassette since this is adisposable part and therefore does not have to be cleaned after use. Thestructure for the air suction thus also does not have to satisfy anyspecial conditions with respect to cleanability.

A layer of air-permeable material, in particular porous material,through which air can be sucked out areally along the plane of thematerial layer in the coupled state of the cassette is advantageouslyarranged on the flexible film at least in part regions. The advantagesof such an arrangement have already been shown above with respect to theapparatus. The layer of an air-permeable material, in particular aporous material, which is arranged on the flexible film allows areliable and uniform areal suction of the air.

The layer of an air-permeable material is advantageously arranged overthe whole area of the flexible film. An inexpensive and simplearrangement can thus be realized in which air can be sucked out over thewhole area between the flexible film and the coupling surface of thetreatment machine.

The layer of an air-permeable material is advantageously welded to thecassette in a peripheral marginal region. The layer of an air-permeablematerial thereby forms a unit with the cassette and is securely heldthereon. Further advantageously, the welding of the layer of anair-permeable material takes place in a single workstep together withthe welding of the film with the hard part. A cost-effective productioncan thus be realized.

Further advantageously, the weld forms a gas-tight barrier along theplane of the material layer. It is hereby ensured by the welding thatair is only sucked out along the plane of the material layer in theregion in which the cassette is pressed with the treatment machine.Otherwise air could be sucked out of side regions and thus prevent aventing of the region between the flexible film and the treatmentmachine. The fact can be utilized in this context that on the welding ofthe layer of an air-permeable material onto the film, the structure ofthe advantageously porous material layer is modified such that agas-tight barrier is created. Sealing is therefore effected with theflexible mat or the coupling surface at this point against a materiallayer made air-impermeable. The layer of an air-permeable material isadvantageously welded to the hard part of the cassette. For thispurpose, the layer of an air-permeable material advantageously comprisesa material which can be welded to the plastic from which the hard partof the cassette is produced.

Alternatively or additionally, the hard part of the cassette can have aperipheral marginal region into which the structure, in particular thelayer of an air-permeable material, does not extend so that thismarginal region forms a sealing web on pressing. This sealing web formedby the marginal region without structure therefore ensures that thespace between the film and the mat or the coupling surface of thetreatment machine can be reliably vented. For this purpose, the layer ofan air-permeable material or a structuring can in particular bedispensed with in the marginal region of the cassette.

Further advantageously, the flexible film is welded to the hard part ofthe cassette in the peripheral marginal region. This peripheral marginalregion can thus be used for the welding to the flexible film as in theprior art and can moreover serve as a sealing web for the structure.

Further advantageously, in the present invention the layer of anair-permeable material is connected, in particular adhesively bondedand/or spot welded and/or pasted and/or laminated and/or tacked to thefilm. A reliable grip of the layer of an air-permeable material on theflexible material is hereby ensured, e.g. even if the layer is notwelded to the hard part in the marginal region.

Further advantageously, with the medical cassette of the presentinvention, the pressure transmitted during the coupling process and/orwith a coupled cassette via the structure, in particular via the layerof an air-permeable material, orthogonally to its plane presses the filmwith the liquid-conducting passages of the hard part of the cassette ina fluid-tight manner. The structure, in particular the layer of anair-permeable material, in contrast remains gas-permeable along itsplane. A reliable pressing of the film and the hard part is thuspossible in which no leaks occur between the liquid-conducting passages,with nevertheless, however, a reliable air suction via the arealstructure remaining possible. This is achieved by a correspondingconfiguration of the material layer, e.g. of a nonwoven, or by thecorresponding configuration of the structuring of the surface of theflexible film.

Further advantageously, the layer made of an air-permeable materialcomprises a non-woven. Such a nonwoven is ideally suited for the uniformtransmission of pressure and for the suction along its plane.

In a further embodiment, the surface of the flexible film of the medicalcassette of the present invention can advantageously have a structuringthrough which air can be sucked out along the plane of the film in thecoupled state of the cassette. It can hereby be achieved in a simplemanner that the air can be reliably removed from the region between thefilm and the mat or between the film and the coupling surface of thetreatment machine without air inclusions or air islands being formed.The arrangement of the structuring on the surface of the film is ofparticular advantage in this connection since the cassette is anywaydisposed of after use and thus does not have to be cleaned.

As already shown with respect to the apparatus for treating a medicalliquid, the structuring advantageously has a net structure and/or ameander-like structure and/or a linear structure. Furtheradvantageously, the structuring is made anisotropic and/orinhomogeneous. It is equally further of advantage for the width of thepassages formed by the structuring to be less than the depth of thesepassages since they thereby do not close on the pressing with thetreatment machine and nevertheless permit a uniform pressing of thesmooth rear of the film with the webs of the hard part.

In a further advantageous embodiment, the structuring extends along theliquid-conducting passages, with use in particular being made of ameander-like and/or a linear structure. The volume which has to beevacuated can hereby be reduced.

Further advantageously, the structuring converges in one or more regionsoutside the liquid-conducting passages which form suction points. Asimple suction can hereby take place in this region, whereas an air-freecoupling is ensured in this region along the liquid-conducting passagesvia the structuring.

The structuring advantageously extends substantially perpendicular tothe passage web edge on the transition from the region withliquid-conducting passages to the region outside the liquid-conductingpassages. A uniform pressing of the film with the passage web edge ishereby ensured with a simultaneously good air suction.

The structuring advantageously has a spacing from the passage web edgesin the regions in which it does not traverse the passage web edges. Itcan hereby be prevented that the liquid spreads over the whole cassettealong the structuring in the event of a rupture. A better pressing ofthe film with the passage web edges is moreover achieved.

The structuring is furthermore advantageously made such that there is nodirect connection between regions of the film with differentliquid-conducting passages. This has the advantage on a rupture of thefilm that the liquid cannot spread over the whole cassette along thestructuring. Ruptures in a region without liquid-conducting passagesthus in particular also remain without consequences. Even on a ruptureof the film in a region of the liquid-conducting passages the liquid isonly sucked to the suction point along the structuring, whereas a leakbeyond the passage web edges between the liquid-conducting passages isprevented.

Further advantageously, the hard part of the medical cassette inaccordance with the invention has containment webs which connect thepassage rim sealing webs and form closed areas in a press-tight manner.The suction point is advantageously disposed in such an area closed in apress-tight manner such that on a film rupture the leak liquid onlyreaches this area and no direct contact is possible between theindividual liquid-conducting regions.

Further advantageously, the medical cassette in accordance with theinvention has at least one suction opening arranged at the hard part ofthe cassette. The space between the film and the mat or the couplingsurface can have a fluid contact for suction via this suction opening.The flexible mat can hereby be made throughgoing and thus ideallycleanable on the machine side.

The suction opening is advantageously arranged outside the region of theliquid-conducting passages in this context. Security is hereby increasedsince a failure of the weld only results in a contamination of thesuction device or of the hydrophobic membrane arranged in the suctionpassage on a simultaneous rupture of the film at a passage point or on asimultaneous failure of a sealing web.

The flexible film is advantageously welded to the hard part of thecassette around the suction opening.

In this context, the annular weld seam around the suction openingadvantageously has a structuring so as not to impair the air suction bythe weld seam. This is in particular important with a structuring of thefilm surface and can e.g. be achieved via a corresponding structure ofthe welding stamp.

Alternatively or additionally, the region of the weld seam can also belowered with respect to the pressing plane of the cassette. Animpairment of the air suction by the weld seam can also be prevented bythis. This is in particular also of particular advantage on the use of alayer of air-permeable material.

Further advantageously, a hydrophobic filter is arranged at the suctionopening. In this context, the suction opening or the suction openingsare advantageously closed by one or more hydrophobic filters in aliquid-tight manner. Hydrophobic filters are liquid-tight andsimultaneously gas-permeable.

The present invention further includes methods for coupling a cassetteto a treatment machine which permit a reliable air-free coupling.

The present invention in this context includes a method for coupling acassette made of a hard part having liquid-conducting passages which arecovered by a flexible film to the coupling surface of a treatmentmachine for treating a medical fluid comprising the steps: coupling ofthe Medical cassette to the coupling surface of the treatment machineand suction of air between the flexible film and the coupling surface ofthe treatment machine during the coupling process and/or with a coupledcassette, with the suction taking place areally via a layer of anair-permeable porous material arranged at least in part regions betweenthe flexible film and the coupling layer. The steps of coupling and ofsuction can be carried out either sequentially in this process or atleast partly simultaneously in that the suction is started while thecoupling process is still ongoing.

Alternatively, the suction can also take place along a structuring ofthe surface of the flexible film and/or along a structuring of a surfaceof a flexible mat facing the flexible film via which the cassette iscoupled to the coupling surface. The advantages already shown withrespect to the apparatus, in particular a reliable suction of the airfrom the region between the flexible film and the coupling surface ofthe treatment machine, hereby result.

The invention furthermore includes a method for coupling a cassette madeof a hard part having liquid-conducting passages which are covered by aflexible film to the coupling surface of a treatment machine fortreating a medical fluid comprising the steps: coupling of the medicalcassette to the coupling surface of the treatment machine via a flexiblemat arranged on the coupling surface, suction of air between theflexible film and the flexible mat during the coupling process and/orwith a coupled cassette, with the suction taking place in regions of theflexible mat without interruptions, and indeed along the plane of theflexible mat and/or through the flexible mat, for which purpose the matcomprises an air-permeable material.

The present invention furthermore includes a method for coupling acassette made of a hard part having liquid-conducting passages which arecovered by a flexible film to the coupling surface of a treatmentmachine for treating a medical fluid comprising the steps: coupling ofthe medical cassette to the coupling surface of the treatment machinevia a flexible mat, in particular a silicone mat, arranged on thecoupling surface and suction of air between the flexible film and theflexible mat during the coupling process and/or with a coupled cassette,with the suction taking place along the plane between the flexible filmand the surface of the flexible mat facing the flexible film. Theadvantages already described above also hereby result. The flexiblematerial can in particular be made inexpensively and easy to clean inthis context.

In this context, in the method in accordance with the invention, amedical cassette and/or an apparatus for treating a medical liquid suchas was/were already shown above is/are advantageously used.

The present invention further relates to a method for checking theleaktightness of a medical cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film, inparticular before the filling of the medical cassette, comprising thesteps: coupling a medical cassette to a coupling surface of a treatmentmachine, suction of air between the flexible film and the couplingsurface of the treatment machine during the coupling process and/or witha coupled cassette, in particular area suction, checking theleaktightness of the medical cassette using the vacuum which arises,with the check of the leaktightness taking place during and/or after thecoupling of the cassette. Since no vacuum can be built up in the case ofa film leak on the suction of the air, it is possible in accordance withthe invention to determine and to display too high a leak rate via thevacuum monitoring and vacuum evaluation of the air suction. A leak inthe disposable film can thus above all be recognized initially beforethe filling of the disposable and before starting treatment. Thedefective disposable can thereby be replaced by an intact one. There isthus the possibility due to the continuous evacuation of determiningleaks in the film and of replacing defective disposables.

This is in particular facilitated by the areal suction of the presentinvention. In contrast, self-seatings would occur between the film andthe mat without the areal suction, which would make a check moredifficult. With such a process, a medical cassette and/or an apparatusfor treating a medical liquid such as have been described above canadvantageously be used.

The applicant reserves the right to file divisional applications to anyaspect of the present invention described in this application, and inparticular also to those aspects which are not the subject matter of theclaims of the present application. In particular, the present inventioncomprises the following aspects, which are subject matter of the presentapplication also on their own and independently of the precedingdescription:

1. An apparatus for treating a medical liquid which includes a treatmentmachine having a coupling surface, with a cassette made of a hard parthaving liquid-conducting passages which are covered by a flexible filmbeing able to be coupled to the coupling surface of the treatmentmachine, characterized in that,

in the coupled state of the cassette, a layer of an air-permeable porousmaterial is arranged between the flexible film and the coupling surface,at least in partial regions, and air can be sucked out areally throughsaid layer during the coupling process and/or with a coupled cassette.

2. An apparatus in accordance with aspect 1, wherein the air can besucked out through the layer of an air-permeable porous material alongthe plane of the layer.

3. An apparatus in accordance with either of aspects 1 or 2, wherein thelayer of an air-permeable porous material is arranged directly on theflexible film in the coupled state of the cassette.

4. An apparatus in accordance with one of the aspects 1 to 3, whereinthe layer of an air-permeable porous material includes a nonwoven.

5. An apparatus in accordance with one of the aspects 1 to 4, whereinthe layer of an air-permeable porous material is arranged over the wholearea on the flexible film.

6. An apparatus in accordance with one of the aspects 1 to 5, whereinthe cassette is pressed with the coupling surface in the coupled state,with the pressure transmitted over the layer made of an air-permeablematerial orthogonally to its plane during the coupling process and/orwith a coupled cassette pressing the film in a fluid tight fashion withthe liquid-conducting passages of the hard part of the cassette, butwith the layer made of an air-permeable material remaining air-permeablealong its plane.

7. An apparatus in accordance with any one of the aspects 1 to 6,wherein the treatment machine has a flexible mat arranged on thecoupling surface, with the cassette being able to be coupled to thecoupling surface of the treatment machine via the flexible mat and alayer of an air-permeable material being arranged between the flexiblefilm and the flexible mat in the coupled state of the cassette.

8. An apparatus for treating a medical liquid which includes a treatmentmachine having a coupling surface and a flexible mat arranged on thecoupling surface, with a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film beingable to be coupled to the coupling surface of the treatment machine viathe flexible mat,

characterized in that

the flexible mat comprises an air-permeable material and is configuredsuch that air is sucked out in a region of the flexible mat withoutinterruptions during the coupling process and/or with a coupledcassette, and indeed along the plane of the flexible mat and/or throughthe flexible mat.

9. An apparatus for treating a medical liquid which includes a treatmentmachine having a coupling surface, with a cassette made of a hard parthaving liquid-conducting passages which are covered by a flexible filmbeing able to be coupled to the coupling surface of the treatmentmachine,

characterized in that

the surface of the flexible film has a structuring through which air canbe sucked out along the structuring of the film during the couplingprocess and/or with a coupled cassette.

10. An apparatus for treating a medical liquid which includes atreatment machine having a coupling surface and a flexible mat arrangedon the coupling surface, with a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film beingable to be coupled to the coupling surface of the treatment machine viathe flexible mat,

characterized in that

the surface of the flexible mat facing the flexible film has astructuring through which air can be sucked out along the structuring ofthe flexible mat during the coupling process and/or with a coupledcassette.

11. An apparatus in accordance with either of aspects 9 or 10, whereinthe structuring has a net structure and/or a meander-like and/or linearstructure.

12. An apparatus in accordance with either of aspects 9 or 10, whereinthe structuring is made anisotropoic and/or inhomogeneous.

13. An apparatus in accordance with either of aspects 9 or 10, whereinthe structuring extends along the liquid-conducting passages.

14. An apparatus in accordance with aspect 13, wherein the structuringconverges in one or more regions outside the liquid-conducting passageswhich form suction points.

15. An apparatus in accordance with one of the aspects 9 to 14, whereinthe structuring extends substantially perpendicular to the passage webedge on the transition from the region with liquid-conducting passagesto the region outside the liquid-conducting passages.

16. An apparatus in accordance with one of the aspects 13 to 15, whereinthe structuring has a spacing from the passage web edges in the regionsin which it does not traverse the passage web edges.

17. An apparatus in accordance with one of the aspects 13 to 16, whereinthe structuring is made such that there is no direct connection betweenregions of the film with different liquid-conducting passages.

18. An apparatus in accordance with one of the aspects 9 to 17, whereinthe cassette is pressed with the coupling surface in the coupled state,with the film being pressed in a fluid-tight manner with theliquid-conducting passages of the hard part of the cassette, but withthe structuring along its plane allowing air transport.

19. An apparatus for treating. a medical liquid which includes atreatment machine having a coupling surface and a flexible mat, inparticular a silicone mat, arranged on the coupling surface, with acassette made of a hard part having liquid-conducting passages which arecovered by a flexible film being able to be coupled to the couplingsurface of the treatment machine via the flexible mat,

characterized in that

air can be sucked out along a plane between the flexible film and thesurface of the flexible mat facing the flexible film during the couplingprocedure and/or with a coupled cassette.

20. An apparatus in accordance with one of the preceding aspectscomprising at least one suction device.

21. An apparatus in accordance with aspect 20, wherein theair-conducting layer is in communication with a vacuum device at one ormore points outside the region of the liquid-conducting passages.

22. An apparatus in accordance with one of the preceding aspects,wherein the suction takes place via at least one valve arranged in thecoupling surface of the treatment machine.

23. An apparatus in accordance with one of the preceding aspects,wherein the suction takes place via one ore more suction openingsarranged in the hard part of the cassette.

24. An apparatus in accordance with one of the preceding aspects,comprising an optical sensor for the recognition of leaks, in particularby scattered light wetting detection.

25. An apparatus in accordance with one of the preceding aspects,comprising a control which carries out an automatic suction of the air.

26. An apparatus in accordance with aspect 25, wherein the controlcarries out An automatic check of the leaktightness of the medicalcassette.

27. An apparatus in accordance with one of the preceding aspects,comprising a medical cassette in accordance with one of the followingaspects.

28. A medical cassette made of a hard part having liquid-conductingpassages which are covered by a flexible film, with the cassette beingable to be coupled to the coupling surface of the treatment machine,

characterized in that

a structure is arranged on the flexible film through which air can besucked out along the plane of the film surface during the couplingprocess and/or with a coupled cassette.

29. A medical cassette in accordance with aspect 28, wherein a layer ofan air-permeable material, in particular porous material, through whichair can be sucked out areally along the plane of the material layer inthe coupled state of the cassette is arranged on the flexible film atleast in part regions.

30. A medical cassette in accordance with aspect 29, wherein the layerof an air-permeable porous material is arranged over the whole area onthe flexible film.

31. A medical cassette in accordance with either of aspects 29 or 30,wherein the layer of an air-permeable material is welded to the cassettein a peripheral marginal region.

32. A medical cassette in accordance with aspect 31, wherein the weldforms a gas-tight barrier along the plane of the layer of anair-permeable material.

33. A medical cassette in accordance with one of the aspects 28 to 32,wherein the layer of an air-permeable material is welded to the hardpart of the cassette.

34. A medical cassette in accordance with either of aspects 28 or 29,wherein the hard part of the cassette has a peripheral marginal regioninto which the structure, in particular the layer of an air-permeablematerial, does not extend so that this marginal region forms a sealingweb on pressing.

35. A medical cassette in accordance with aspect 34, wherein theflexible film is welded to the hard part of the cassette in theperipheral marginal region.

36. A medical cassette in accordance with aspect 29, wherein the layerof an air-permeable material is connected, in particular adhesivelybonded and/or spot welded and/or pasted and/or laminated and/or tackedto the film.

37. A medical cassette in accordance with either of aspects 28 or 29,wherein the pressure transmitted during the coupling process and/or witha coupled cassette via the structure, in particular via the layer of anair-permeable material, orthogonally to its plane presses the film withthe liquid-conducting passages of the hard part of the cassette in afluid-tight manner, but the structure, in particular the layer of anair-permeable material remains gas-permeable along its plane.

38. A medical cassette in accordance with aspect 29, wherein the layerof an air-permeable porous material includes a nonwoven.

39. A medical cassette in accordance with aspect 28, wherein the surfaceof the flexible film has a structuring through which air can be suckedout along the plane of the film in the coupled state of the cassette.

40. A medical cassette in accordance with aspect 39, wherein thestructuring has a net structure and/or a meander-like structure and/or alinear structure.

41. A medical cassette in accordance with either of aspects 39 or 40,wherein the structuring is made anisotropic and/or inhomogeneous.

42. A medical cassette in accordance with either of aspects 39 or 40,wherein the structuring extends along the liquid-conducting passages.

43. A medical cassette in accordance with aspect 42, wherein thestructuring converges in one or more regions outside theliquid-conducting passages which form suction points.

44. A medical cassette in accordance with one of the aspects 28 to 43,wherein the structuring extends substantially perpendicular to thepassage web edge on the transition from the region withliquid-conducting passages to the region outside the liquid-conductingpassages.

45. A medical cassette in accordance with one of the aspects 42 to 44,wherein the structuring has a spacing from the passage web edges in theregions in which it does not traverse the passage web edges.

46. A medical cassette in accordance with one of the aspects 42 to 45,wherein the structuring is made such that there is no direct connectionbetween regions of the film with different liquid-conducting passages.

47. A medical cassette in accordance with one of the preceding aspects,wherein the hard part has containment webs which connect the passage rimsealing webs and form areas sealing pressed closed.

48. A medical cassette in accordance with one of the preceding aspects,comprising at least one suction opening arranged in the hard part of thecassette.

49. A medical cassette in accordance with aspect 48, wherein the suctionopening is arranged outside the region of the liquid-conductingpassages.

50. A medical cassette in accordance with aspect 48, wherein theflexible film is welded to the hard part of the cassette around thesuction opening.

51. A medical cassette in accordance with aspect 50, wherein the annularweld seam has a structuring around the suction opening.

52. A medical cassette in accordance with aspect 50, wherein the regionof the weld seam is lowered with respect to the pressing plane of thecassette.

53. A medical cassette in accordance with aspect 48, wherein ahydrophobic filter is arranged at the suction opening.

54. A method for coupling a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film to thecoupling surface of a treatment machine for treating a medical fluidcomprising the steps:

coupling the medical cassette to the coupling surface of the treatmentmachine;

suction of air between the flexible film and the coupling surface of thetreatment machine during the coupling process and/or with a coupledcassette,

characterized in that

the suction takes place areally via a layer of an air-permeable porousmaterial arranged at least in part regions between the flexible film andthe coupling surface.

55. A method for coupling a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film to thecoupling surface of a treatment machine for treating a medical fluidcomprising the steps:

coupling the medical cassette to the coupling surface of the treatmentmachine via a flexible mat arranged on the coupling surface;

suction of air between the flexible film and the flexible mat during thecoupling process and/or with a coupled cassette,

characterized in that

the suction takes place in regions of the flexible mat withoutinterruptions, and indeed along the plane of the flexible mat and/orthrough the flexible mat, for which purpose the mat comprises anair-permeable material.

56. A method for coupling a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film to thecoupling surface of a treatment machine for treating a medical fluidcomprising the steps:

coupling the medical cassette to the coupling surface of the treatmentmachine;

suction of air between the flexible film and the coupling surface of thetreatment machine during the coupling process and/or with a coupledcassette,

characterized in that

the suction takes place along a structuring of the surface of theflexible film and/or along a structuring of a surface of a flexible matfacing the flexible film via which the cassette is coupled to thecoupling surface.

57. A method for coupling a cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film to thecoupling surface of a treatment machine for treating a medical fluidcomprising the steps:

coupling the medical cassette to the coupling surface of the treatmentmachine via a flexible mat arranged on the coupling surface;

suction of air between the flexible film and the flexible mat during thecoupling process and/or with a coupled cassette,

characterized in that the suction takes place along the plane betweenthe flexible film and the surface of the flexible mat facing theflexible film.

58. A method in accordance with any one of the aspects 54 to 57,comprising a medical cassette and/or an apparatus for treating a medicalliquid in accordance with one of the aspects.

59. A method for checking the leaktightness of a medical cassette madeof a hard part having liquid-conducting passages which are covered by aflexible film, in particular before the filling of the medical cassette,comprising the steps:

coupling the medical cassette to a coupling surface of a treatmentmachine;

suction of air between the flexible film and the coupling surface of thetreatment machine, in particular areal suction during the couplingprocess and/or with a coupled cassette;

checking the leaktightness of the medical cassette with reference to thecreated vacuum,

wherein the check of the leaktightness takes place during and/or afterthe coupling of the cassette.

60. A method in accordance with aspect 59, comprising a medical cassetteand/or an apparatus for treating a medical liquid in accordance with oneof the preceding aspects.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be shown in more detail with reference toembodiments and to drawings. There are shown:

FIG. 1: an apparatus for treating a medical liquid in accordance withthe prior art;

FIG. 2: an apparatus for treating a medical liquid in accordance with afirst embodiment of the present invention;

FIG. 3: an apparatus for treating a medical liquid in accordance with asecond embodiment of the present invention;

FIG. 4: a plan view as well as a sectional view of a structuring inaccordance with a third embodiment of the present invention;

FIG. 5a : a plan view of a medical cassette in accordance with a fourthembodiment of the present invention;

FIG. 5b : a sectional view through a structuring in a region withsealing webs;

FIG. 5c : a sectional view through an embodiment of a suction opening inaccordance with the invention; and

FIG. 6: an apparatus for treating a medical liquid in accordance with afifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

FIG. 1 shows an apparatus for treating a medical liquid such as is usedin the prior art, e.g. for hemodialysis or peritoneal dialysis. Suchapparatus can, however, also be used in a plurality of other fields ofapplication in which a disposable cassette, which is also called adisposable, is used and is coupled to sensors and actuators of atreatment machine via a coupling surface.

The treatment machine 1 has a coupling surface 10 on which a sensor 11is arranged by way of example. The cassette 2 includes a hard part 20having a liquid-conducting passage 21 which is covered by a flexiblefilm 25, with the liquid-conducting passage being separated influid-tight manner inside the cassette via laterally arranged sealingwebs 22 which are pressed with the flexible film 25. In this connection,the sensor 11 is disposed opposite the liquid-conducting passage 21which thus forms a measuring chamber, in the case of a pressure sensor apressure measuring chamber.

Furthermore, a flexible silicone mat 15 is arranged between the film 25and the coupling surface 10 of the treatment machine 1 on the machineside to protect the sensor surfaces of the sensor 11 from environmentalinfluences. In addition, the machine surface is hereby hermeticallysealed and thus ideally hygienically cleanable. Alternatively, however,the silicone mat 15 can also be dispensed with so that the film 25directly contacts the coupling surface 10 of the treatment machine 1.

The difficulty exists with the coupling of sensors to the filmdisposable 2, however, of coupling the film 25 to the sensor surface ofthe sensor 11 such that correct measured values are obtained. Inparticular air which is enclosed in the transmission path between thedisposable film 25 and the sensor surface on the insertion of thecassette produces a falsification of the measured results. This appliesto pressure sensors, but also e.g. in level detection and likewise toactuators such as valves which control the liquid flows inside thecassette via a pressing of the flexible film 25 into theliquid-conducting passages 21 of the hard part 20.

A first embodiment of the present invention is now shown in FIG. 2. Inthis context, an areal structure between the film 25 and the mat 15permits an areal air suction along the coupling plane. It can hereby beensured that the space between the film 25 and the mat 15 is reliablyvented without air islands remaining enclosed and falsifying themeasured results due to a self-sealing by applying the film 25 to themat 15.

In the embodiment shown in FIG. 2, the areal suction is achieved in thata layer 30 of an air-permeable, in particular porous, material, in thiscase a nonwoven layer, is inserted between the film 25 and the mat 15.Such a nonwoven layer is porous due to its structure, that is air canflow in the surface in this layer even if the total composite of film25, nonwoven 30 and mat 15 is strongly pressed e.g. by the sealing webs22.

A connection is thus obtained between the film 25 and the hard part 20which is pressed in a fluid-tight manner, with the layer 30 of anair-permeable material, in particular porous material, neverthelessremaining permeable for air. It is thus sufficient to contact the spacebetween the film 25 and the mat 15 at a single point with a vacuumsystem 13 in a fluid manner via a suction opening 28 to vent the totalspace between the film 25 and the mat 15 reliably and areally. Aplurality of sensors 11 or actuators can hereby be coupled reliably andair-free to the film 25. The connection of the nonwoven space with thevacuum system can in this manner also be used directly after thepressing for a film leaktightness test such as would not be possiblewithout such an air conducting layer.

The suction opening 28 is integrated in the hard part 20 of the cassettein the first embodiment and has a hydrophobic membrane 24 in the suctionpassage which is likewise integrated into the hard part. A contaminationof the machine can hereby be prevented in the defect case of a filmrupture. The suction opening 28 in the hard part 20 of the cassette isconnected via a sealing element 14 to suction channels which areintegrated in the machine door 12 and are in turn in communication witha vacuum system 13 on the insertion of the cassette into the treatmentmachine. The films has a peripheral weld with the hard part around thesuction opening 28. In this context, the region of the peripheral weldis lowered with respect to the pressing level of the cassette so thatthe weld of the nonwoven 30 with the hard part does not represent abarrier for the air suction.

The fluid contacting of the nonwoven space takes pace outside theliquid-conducting areas of the passage structure 21. A failure of theweld between the film and the hard part around the suction opening thusonly results in a contamination of the hydrophobic membrane 24 on asimultaneous film rupture on a passage point or a simultaneous failureof a sealing web 22.

A second embodiment of the present invention is shown in FIG. 3 in whichthe fluid contacting does not take place starting from the hard part 20,but rather from the mat side. In this connection, an opening is providedin the mat 15 and is in fluid communication with the vacuum system 13via a valve 16. The contacting of the air-conducting layer 30 also takesplace outside the region of the liquid-conducting areas of the passagestructure 21 here. The hard part 20 has a plunger 29 which opens thevalve 16 on the insertion of the cassette into the treatment machine.The cassette has a peripheral sealing web 27 at which no nonwoven layer30 is provided so that an outwardly closed space arises between the film25 and the mat 15 from which the air can be sucked out without leak airflowing in from the outside.

Alternatively to the arrangement shown in FIG. 3, an excessive intrusionof leak air into the system can also take place by other designs of aperipheral sealing rim. The fact can e.g. be utilized in this contextthat the nonwoven structure is modified on the welding of the nonwoven30 to the film 25 such that a gas-tight barrier is created. A nonwoven30 made air-impermeable can therefore be pressed with the silicone mat15 at this point in an airtight manner. This welding ideally takes placein a single workstep together with the welding of the film with the hardpart 20. For this purpose, it is advantageous to produce the nonwoven 30from a material, e.g. from PP, which can welded with the hard part 20.

A further possibility comprises cutting out the nonwoven to be smallerthan the film so that a seal can be provided peripherally directlybetween the film and the silicone mat. The fastening of the nonwoven 30to the film can take place in this case e.g. by adhesive bonding and/orspot welding and/or pasting and/or laminating and/or tacking. It ismoreover possible to connect the film and the nonwoven in a firstworkstep and then to establish the connection to the hard part in asecond step.

Alternatively to the use of the nonwoven shown in the first and secondembodiments, the air transport in the desired plane can be achieved inthat the surface of the film 25 is structured such that anair-conducting layer arises in the film itself. This can take place, forexample, by stamping a structure into the film.

In this context, in a third embodiment, a grid-like structure can bepressed into the film so that a network of grooves 35 forming passages,generally designated by reference numeral 37, arises in the film whichare separated from one another by regions of thicker material. Differentgeometries are conceivable, with FIG. 4 showing a honeycomb structure byway of example. It is also possible to realize an anisotropic suction bythe selection of the suitable structure in that e.g. the grooves 35forming the passages 37 are made larger from left to right than from topto bottom. The structure on the surface can also be inhomogeneous indesign. The structure can likewise be of meander shape.

In this context, the geometry of the passages being created is importantfor the achievable suction power. Narrow, deep grooves form passagesthat are not closed by the silicone mat on pressing so that a suctionthrough the passages remains possible. The shallower the grooves andresulting passages are, the higher the risk of sealing by a partialapplication of the film to the mat in the passages. If the passagesbecome too wide, risk increases that the pressing on the smooth side ofthe film (toward the blood side and the hard part) becomes tooinhomogeneous and that leaks arise on this side. Further productionprocesses for the manufacture of the structuring of the surface of thefilm are available in addition to stamping. A structure can e.g. also beintroduced into the film surface directly in the extrusion of the film.

Alternatively, such a structuring could also be arranged in the surfaceof the mat 15 facing the film 30. A reliable air suction could alsohereby be made possible. However, it is a disadvantage of such anarrangement that the surface of the mat is then no longer smooth and soa cleaning of the mat surface is made difficult.

It is alternatively likewise possible to dispense with the silicone mat15 on the use of a nonwoven 30 or of a structuring of the film surfaceso that the nonwoven 30 is arranged directly between the film 25 and thecoupling surface 10 of the treatment machine or the structured surfaceof the film 25 directly contacts the coupling surface 10 of thetreatment machine.

On the full area structuring of the cassette film or by generating afull area drainage layer between the film plane and the coupling plane,the total film area of the cassette up to the peripheral film weld seamA or up to the outer peripheral sealing web 8 (produced at the cassetteside or at the machine side) is made passable for gases and liquidsbeyond all the regular passage rim sealing webs C. On the initialintegrity test, it is therefore necessary to evacuate the whole area andthe leaktightness of the peripheral sealing web must also be ensuredparallel to the actually desired leaktightness of the passage rims sothat the treatment can be enabled. The air quantity to be sucked outinitially for this purpose and the time required for this purpose arethereby increased and the detection reliability for the relevant filmruptures is lowered.

A fourth embodiment of the present invention is therefore shown in FIG.5a in which an internal structure of the structured surface of the filmis used. Only the liquid-wetted film areas required from a technicalprocess aspect are made capable of drainage in the internal structure.The pressing between the outer side of the film and the coupling planeis significantly lower than the pressing on the passage rim sealing websand in the non-liquid areas G and H. In these latter areas, the cassettehas flat sealing bases parallel to the film. Whereas the passage rimsealing webs are configured such that the liquid cannot overflow in thenormal case, the areas G and H are configured such that liquid which haspenetrated does not find any space since the pressing of the rubber mateffects an approximately full contact of the film both to the cassetteplane and to the lowered rubber plane.

Since the pressing between the film and the rubber mat is significantlylower in the liquid-wetted internal areas S1, S2 and S3 than thepressing in all other areas of the film zone, a much less pronounceddrainage structure is sufficient in this area both to ensure thecomplete film coupling and to ensure the complete detection of therelevant film surface with respect to possible ruptures. A safetyspacing E of the structure D of approximately up to 1 mm can thereforebe provided in the internal structure to the passage web edges C.

The areas G and H are covered by the sterilization process andhermetically sealed toward the outer world. If now a rupturenevertheless occurs in the region of the area G during the treatment,that is after an initial integrity test without findings, this as a ruleremains without consequence for the treatment since the relevant areas Sare not affected and since there is no possibility of the liquidentering into the area G. If a rupture occurs at a passage sealing weband beyond it, as sketched by F, the functions of the self-sealing comeinto effect due to the high pressings between the smooth film and thesmooth rubber mat and furthermore due to the additional pressing on theperipheral rim. If a rupture occurs in the internal areas S during thetreatment, the leak fluid penetrates into the space between the film andthe rubber mat, further reduces the pressing and is finally pressed upto and onto the suction point K along the anisotropic structure D. Eventhe collection area H is only insignificantly filled with leak fluid inthis context since the path over the direct conducting paths I to thesuction point K offers the lowest flow resistance.

The internal structure provides less detection time and higher detectionaccuracy in the integrity test before the filling with treatment liquid.The internal structure provides redundant passive leak protection in thefirst defect case of the film rupture during treatment. The internalstructure provides a much smaller area of the film and rubber mat whichcan be wetted on film rupture and which can, vice versa, contribute tothe contamination of the treatment surface in the treatment liquid. Theinternal structure can increase the reliability and reduces thedetection time of an occurring film rupture during the treatment andthus increases the security against contamination andcross-contamination. The internal structure can reduce the probabilityand the extent of possible liquid losses to the outside.

The possibility of an anisotropic structure furthermore results: Ananisotropic film structure or an anisotropic design of intersperseddrainage layers means designing the intensity, the direction, thefunctionality and the non-presence of the drainage effect locallydifferently. This includes the previously described internal structurewith an unstructured marginal region toward the passage sealing webs.

The next possibility is the deliberate provision of separate structureareas S1 . . . S3 with a minimized number of crossings I of passagesealing web regions. I also shows how a minimum of volume has to besucked out or wetted due to the optimized structure in the case of theinitial test and in the case of a leak.

The sectional representation FIG. 5b shows the optimized effect oflinear structures which cross the passage rim sealing webs inperpendicular manner. An optimum of pressing leaktightness on the liquidside can be linked with an optimum obtaining of drainage structure depthon the machine side by this arrangement. The two basically negativedesigns of structures are shown with extreme exaggeration in the Figure,namely a partial squeezing closure U of the structure passages D and apressing V interrupted by the inhomogeneous force conduction at thepassage rim sealing webs C. Structures crossing the sealing webs inparallel or obliquely would penetrate further into the web and into therubber mat and thus more greatly reduce the drainage effect and thepressing effect.

It must also be considered that it may be necessary at certain points,for example for the optical measurement of the liquid turbidity, or atpassage points for ultrasound, that the film remains smooth and/ortranslucent. In this case, a window is provided by omission of structureor of drainage layers.

Possibilities furthermore result by the use of containment webs. Ifconnection webs J are added between the passage rim sealing webs atsuitable points of the passage and chamber layout, new areas H sealingpressed closed are obtained. If the drainage structures converge in thisarea, this area H forms the total area together with the liquid areas S1. . . S3 which is detected for film rupture before and during thetreatment and which has a passively sealing pressed passage rim as anareal boundary for the conceivable leak fluid or for the conceivablecontamination and cross-contamination. Each leak must finally reach thisarea H and this is the preferred location for suction points K with leakdetectors and with hydrophobic contamination membranes.

Containment webs furthermore provide the possibility of somewhatreducing the pressing sealing effect at the points of the crossings I ofthe drainage structures over the passage sealing rims in favor of abetter drainage effect (for example by a widening of the passage rimsealing webs) without outwardly reducing the effect of the reliablepressing leaktightness.

The present invention furthermore provides the possibility of anon-invasive blood leak detection: The decision to cover the couplingplane of the machine with a closed protective layer, for instance ofrubber, requires the consequence of also making a leak detector for theearly discovery of film ruptures during the treatment as a deviceworking in a non-invasive manner. This is, for example, possible througha thin rubber mat via capacitive sensors, via ultrasonic sensors or viathe detection of the vacuum collapsing on a leak. This is possible viaoptical sensors with a reflection arrangement on the side of the matingcoupling plane (to the nonfilm side of the cassette). A color sensorcan, for example, distinguish in this context whether blood has exitedor whether it is a normal moisture. The structure of the film can beutilized here to install a scattered light wetting detection. With a dryfilm, scattered light is reflected back at the structure which is absentif the structure is liquid-wetted. With such an arrangement on the nonrubber mat side, the necessity for a sensor-sensitive special design ofthe rubber mat is therefore dispensed with.

Possibilities furthermore result due to specially structured weld seamsand rubber mats: The problem in particular arises at the suction point Kdue to the annular weld seams required for this purpose around thehydrophobic membrane and around the hydrophobic membrane cut-out or thesuction hole cut-out in the film that both a structure of the film and awelding on a drainage layer (for instance made of a nonwoven) disposedthereabove are leveled by an annular weld seam and thereby form annularbarriers between the areas H and K.

To cancel these barrier possibilities, FIG. 5c shows a combination offour possible measures. A dent Q in the rubber mat equally reduces thesealing pressing against the annular weld seam as a dent R in thecassette surface. A further similar effect is achieved by the localstructure S of the rubber mat in the region of the dent with grooves andpatterns which radially bridge the weld seam at a plurality of pointswith a drainage effect.

The disadvantage of a worsened cleaning capability of the rubber matresults with both rubber mat measures. The counterpart to a structure ofthe rubber mat in the region of the suction point is a structure of theannular weld seam. For this purpose, the welding stamp is configured tobe annular, but this ring is made more pronouncedly conically than theassociated weld surface of the cassette. The annular surface M isfurthermore equipped with radially arranged drainage ribs which leave acommon structure of the cassette base and the film during welding, saidcommon structure having a serrated annular surface with radiallyoutwardly facing linear structures which extend up to and into theunwelded film regions after the welding due to the conical shape of theannular surface association, said linear structures form a totalstructure together with the radial structures already present therewhich is no longer interrupted by the annular sealing weld zone.

FIG. 6 now shows a fifth embodiment of the apparatus for treating amedical liquid of the present invention in which the suction does nottake place by an additional nonwoven between the flexible film 25 andthe flexible mat 15 or by a corresponding structuring, but rather by thesuitable choice of the mat material via the flexible mat 15 itself. Forthis purpose, the flexible mat comprises an air-permeable material (e.g.silicone) such that the air between the flexible mat 15 and the flexiblefilm 25 can be sucked out directly through the mat 15 itself via thevacuum applied to the suction passages 40. The wide area distribution ofthe vacuum takes place in this context via the air passages 40 in themachine plate, whereas the permeable mat then permits an areal suctionover the total surface. A complete closure of the suction is alsopractically precluded by this areal design.

In this embodiment, an already known medical cassette 2 made of a hardpart 20 having liquid-conducting passages 21 can be used which is sealedby the flexible film 25. For this purpose, as in known systems, themedical cassette 2 is pressed with the flexible mat 15 of the treatmentmachine so that the sealing webs 22 provide a seal. In accordance withthe invention, however, an areal suction is now possible which takesplace via the vacuum passages 40 and via the permeable mat material onthe machine side.

The mat material is advantageously air-permeable, but liquid-tight, inthis context to avoid contamination of the coupling surface and tofacilitate cleaning.

The possibility of determining leaks in the film moreover results by thepossibility in accordance with the invention of sucking out aircontinuously between the flexible film 25 and the coupling surface 10.No vacuum can be built up after the pressing of the door in the case ofa sufficiently large film leak due to the areal evacuation. Accordingly,air is constantly sucked out of the still unfilled disposable into theintermediate space between the film and the mat or the coupling surface.The too high leak rate can then be determined and registered via thevacuum monitoring and the vacuum evaluation. The check of theleaktightness can take place during and/or after the coupling to thecassette.

A leak in the disposable film can thus above all be recognized initiallybefore the filling of the disposable and before starting treatment. Thedefective disposable can thereby be replaced by an intact one.

Without the areal suction, in contrast, such a check would be lessreliable since a self-sealing can arise between the film and the mat andfilm leaks could still be present in regions with enclosed air islands,which leaks would not be detected via the vacuum monitoring and thevacuum evaluation. Basically, the check in accordance with the inventioncan, however, be carried out with any type of evacuation.

In this connection, the central idea of the invention is the arealsuction of the air between the flexible film and the coupling surface,which is made possible by the different embodiments in that anair-permeable layer, a structuring of the surface of the flexible filmand/or mat, a suction in the plane between the flexible mat and theflexible film and/or a suction through a permeable mat material is/areprovided.

The invention being thus described, it will be apparent that the samemay be varied in many ways. Such variations are not to be regarded as adeparture form the spirit and scope of the invention, and all suchmodifications as would be recognized by one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. An apparatus for treating a medical liquidcomprising a treatment machine having a coupling surface, with acassette made of a hard, part having liquid-conducting passages whichare covered by a flexible film being able to be coupled to the couplingsurface of the treatment machine, a surface of the flexible film facingthe coupling surface of the treatment machine having a structuring, saidstructuring being formed by grooves that are recessed in the surface ofthe flexible film, the grooves forming passages through which air can besucked out along the structuring of the film during the coupling processand/or with a coupled cassette.
 2. An apparatus for treating a medicalliquid comprising a treatment machine having a coupling surface and aflexible mat arranged on the coupling surface, with a cassette made of ahard part having liquid-conducting passages which are covered by aflexible film being able to be coupled to the coupling surface of thetreatment machine via the flexible mat, a surface of the flexible matfacing the flexible film having a structuring, said structuring beingformed by grooves that are recessed in the surface of the flexible mat,the grooves forming passages through which air can be sucked out alongthe structuring of the flexible mat during the coupling process and/orwith a coupled cassette.
 3. The apparatus in accordance with claim 1,wherein the structuring has a net structure and/or a meander-like and/orlinear structure.
 4. The apparatus in accordance with claim 1, whereinthe structuring is made anisotropoic and/or inhomogeneous.
 5. Theapparatus in accordance with claim 1, wherein the structuring extendsalong the liquid-conducting passages.
 6. The apparatus in accordancewith claim 5, wherein the structuring converges in one or more regionsoutside the liquid-conducting passages which form suction points.
 7. Theapparatus in accordance with claim 1, wherein the structuring extendssubstantially perpendicular to a passage web edge on a transition froma-region with liquid-conducting passages to a region outside theliquid-conducting passages.
 8. The apparatus in accordance with claim 5,wherein the structuring has a spacing from the passage web edges in theregions in which it does not traverse the passage web edges.
 9. Theapparatus in accordance with claim 5, wherein the structuring is madesuch, that there is no direct connection between regions of the filmwith different liquid-conducting passages.
 10. The apparatus inaccordance with claim 1, wherein the cassette is pressed with thecoupling surface in the coupled state, with the film being pressed in afluid-tight manner with the liquid-conducting passages of the hard partof the cassette, but with the structuring along its plane allowing airtransport.
 11. The apparatus in accordance with claim 1, wherein theapparatus includes at least one suction device.
 12. The apparatus inaccordance with claim 11, wherein the structuring is in communicationwith a vacuum device at one or more points outside the region of theliquid-conducting passages.
 13. The apparatus in accordance with claim1, wherein suction takes place via at least one valve arranged in thecoupling surface of the treatment machine.
 14. The apparatus inaccordance with claim 1, wherein suction takes place via one ore moresuction openings arranged in the hard part of the cassette.
 15. Theapparatus in accordance with claim 1, wherein the apparatus includes anoptical sensor for the recognition of leaks.
 16. The apparatus inaccordance with claim 1, wherein the apparatus includes a vacuum devicethat carries out an automatic suction of the air.
 17. The apparatus inaccordance with claim 16, wherein the vacuum device carries out anautomatic check of the leaktightness of the cassette.
 18. A medicalcassette made of a hard part having liquid-conducting passages which arecovered by a flexible film, with the cassette be able to be coupled to acoupling surface of a treatment machine, a surface of the flexible filmfacing the coupling surface of the treatment machine having astructuring, said structuring being formed by grooves that are recessedin the surface of the flexible film, the grooves forming passagesthrough which air can be sucked out along the plane of the film in thecoupled state of the cassette.
 19. The medical cassette in accordancewith claim 18, wherein the hard part of the cassette has a peripheralmarginal region into which the structuring does not extend so that thismarginal region forms a sealing web on pressing.
 20. The medicalcassette in accordance with claim 19, wherein the flexible film iswelded to the hard part of the cassette in the peripheral marginalregion.
 21. The medical cassette in accordance with claim 18, whereinthe structuring has a net structure and/or a meander-like structureand/or a linear structure.
 22. The medical cassette in accordance withclaim 18, wherein the structuring is made anisotropic and/orinhomogeneous.
 23. The medical cassette in accordance with claim 18,wherein the structuring extends along the liquid-conducting passages.24. The medical cassette in accordance with claim 18, wherein thestructuring converges in one or more regions outside theliquid-conducting passages which form suction points.
 25. The medicalcassette in accordance with claim 18, wherein the structuring extendssubstantially perpendicular to a passage web edge on a transition from aregion with liquid-conducting passages to a region outside theliquid-conducting passages.
 26. The medical cassette in accordance withclaim 23, wherein the structuring has a spacing from the passage webedges in the regions in which it does not traverse the passage webedges.
 27. The medical cassette in accordance with claim 23, wherein thestructuring is made such that there is no direct connection betweenregions of the film with different liquid-conducting passages.
 28. Themedical cassette in accordance with claim 18, wherein the hard part hascontainment webs which connect passage rim sealing webs and form areassealing pressed closed.
 29. The medical cassette in accordance withclaim 18, the cassette includes at least one suction opening arranged inthe hard part of the cassette.
 30. The medical cassette in accordancewith claim 29, wherein the suction opening is arranged outside theregion of the liquid-conducting passages.
 31. The medical cassette inaccordance with claim 29, wherein the flexible film is welded to thehard part of the cassette around the suction opening by an annular weldseam.
 32. The medical cassette in accordance with claim 31, wherein theannular weld seam has a structuring around the suction opening.
 33. Themedical cassette in accordance with claim 31, wherein a region includingthe weld seam is lowered with respect to a pressing plane of thecassette.
 34. The medical cassette in accordance with claim 29, whereina hydrophobic filter is arranged at the suction opening.
 35. A methodfor coupling a medical cassette made of a hard part havingliquid-conducting passages which are covered by a flexible film to acoupling surface of a treatment machine for treating a medical fluidcomprising the steps: coupling the medical cassette to the couplingsurface of the treatment machine; suctioning of air between the flexiblefilm and the coupling surface of the treatment machine during thecoupling process and/or with a coupled cassette, said suctioning of airtaking place along a structuring of a surface of the flexible film thatfaces the coupling surface of the treatment machine, structuring beingformed by grooves that are recessed in the surface of the flexible film,the grooves forming passages for suction of air and/or along astructuring of a surface of a flexible mat facing the flexible film,said structuring being formed by grooves that are recessed in thesurface of the flexible mat, the grooves forming passages for suction ofair.